Pressure switch

ABSTRACT

In one modification the diaphragm pad or plate has a post engaging the spring seat which fits loosely in the housing to avoid interference. The spaced shoulders between the spring seat and the post provide the necessary lost motion connection to the switch actuating tongue which fits over and guides the post. In the other modification the post is guided by the tongue which fits in the notches on the post. The spring seat member is eliminated and the spring seats on the post. This design reduces the number of requisite parts and reduces friction impairing repeatability of the performance.

United States Patent [72] Inventors Erich Kothe; 3,178,531 4/1965 Dawson et a1. ZOO/83.9 William D. Gruhn, Jr., both of Addison, 111. 3,209,094 9/1965 Bauer ZOO/83.9 (21 1 Appl. No. 848,854 3,436,502 4/1969 Egli 200/839 :iled d FOREIGN PATENTS atente u y Assign Controls p y 0 America 1,281,530 10/1968 Germany ZOO/83.9

M l P -k, I", Primary ExaminerRobert K. Schaefer Assistant Examiner-William J. Smith Attorneys-John W. Michael, Gerrit D. Foster, Bayard H. PRESSURE SWITCH Michael, Paul R. Puerner, Joseph A, Gemignani, Andrew 0.

5 Claims, 4 Drawing g Riteris and Daniel Van Dyke [52] U.S.Cl 200/83 [51) Int. Cl H0111 35/34 [50] Field of Search 200/8334, ABSTRACT; I o e modification the diaphragm pad or plate 839 has a post engaging the spring seat which fits loosely in the housin to avoid interference. The spaced shoulders between [56] acre and the spring seat and the post provide the necessary lost motion UNlTED STATES PATENTS connection to the switch actuating tongue which fits over and 2,636,093 4/1953 Clark et a1. ZOO/83.9 guides the post. in the other modification the post is guided by 2,921,158 1/1960 Tay1or..... ZOO/83.9 the tongue which fits in the notches on the post. The spring 2,975,251 3/1961 Beller ZOO/83.9 seat member is eliminated and the spring seats on the post. 3,1 10,784 1 1/ 1963 Wi1liams et a1. ZOO/83.9 This design reduces the number of requisite parts and reduces 2,813,944 1 1/1957 Tyzack ZOO/83.9 friction impairing repeatability of the performance.

u eeqe PRESSURE SWITCH BACKGROUND OF INVENTION Pressure switches have heretofore employed a construction in which the diaphragm plate motion was transmitted to the actuating tongue of the switch by means of a separate loose actuator resting on top of the plate and engaging the actuating tongue of the switch. The diaphragm motion was opposed and the switch calibration was determined by a compressed spring seated on a seat member having a boss depending through the housing and guided by the housing while engaging and opposing the actuator unit. Guidance for the actuator and spring seat was obtained by the fit of the spring seat boss where it passes through the housing. Occasionally this could and did cause some friction which, of course, affected the operation of the pressure switch. It also became desirable to reduce the number of parts and this reduction in parts along with the elimination of friction is the area to which the present invention is directed.

SUMMARY OF INVENTION In the new construction one modification employs a diaphragm plate provided with an integral post having a central pin which is received in a cooperating hole in the boss depending from the spring seat. The length of the pin and the depth of the hole determine the spacing between the facing portions of the boss and post and this, in turn, defines the slot in which the actuating tongue of the switch is received with a lost-motion connection. The lost-motion connection is the means by which motion differential and thus pressure differential is obtained on the trip and reset points of the switch operation. The boss is loosely fitted in the hole through the housing and the assembly is guided by an extra center tongue in the switch blade assembly. With this construction the former actuator piece has been eliminated and thus one part has been eliminated. Furthermore, there is no friction between the spring seat and its boss and the housing. Accordingly, the cost of the switch has been reduced while improving the performance of the switch.

In the second modification the trip spring is seated directly on a post formed from the diaphragm plate and suitably slotted to provide the lost-motion connection to the switch actuating tongue while receiving the guidance tongue whereby the single post formed from the diaphragm plate itself provides all functions of guidance and lost-motion connection. This, of course, further eliminates a part, namely the separate spring seat.

DESCRIPTION OF DRAWINGS FIG. I is a vertical section through one modification.

FIG. 2 is a section taken on line 2-2 of FIG. 1.

FIG. 3 is a vertical section through a second modification.

FIG. 4 is an enlarged fragmentary section on line 4-4 in FIG. 3.

DESCRIPTION OF PREFERRED EMBODIMENTS The pressure switch housing is made up of the molded plastic portion with the metal lower portion 12 crimped over the plastic part and capturing the diaphragm l4 therebetween. The metal housing part has connection 16 for transmitting pressure variations (usually air) to the underside of the diaphragm. On top of the diaphragm there is a diaphragm plate or pad 18 having an integral central post 20 which includes the pin 22. It will also be noted the diaphragm is provided with a plurality of holes receiving the upwardly projecting nubs 24 of the diaphragm and locating the plate with respect to the diaphragm.

The pin 22 of the central post 20 is received in the cooperating hole in the boss 26 depending from the spring seat member 28. The length of the pin and the depth of the hole determine the spacing between the facing portions of the boss 26 and the post 20.

The spring seat 28 serves to seat and center spring 30 which is received in the inverted cup 32 which can be variably positioned by the mechanism 34 to determine the degree of compression of the spring and, hence, the calibration of the pressure switch.

The inside portion of the switch blade includes an actuating tongue 36 which receives the motion from the diaphragm. This is accomplished by engaging the inside portions 38 of the tongue in the space between the facing portions of the spring seat boss 26 and the post 20. This will, of course, give a lostmotion connection determined by the spacing between the boss and the post and this is the manner in which a large motion differential and thus a large pressure differential for a given spring rate of the trip spring is obtained. It will be noted that the switch includes a central tongue 40 which is apertured to fit over the post 22 and thus the central tongue guides the post and the spring seat boss. Therefore, the spring seat boss need not be guided at the aperture in the housing where it passes into the space above the diaphragm. It is for this reason there is quite ample clearance so as to avoid any possibility of frictional engagement at that point and thus all friction is eliminated. It will be understood that as the diaphragm moves upwardly from the position indicated the actuating tongue 36 and, of course, the guide tongue 40 move upwardly until the barrel spring 43 passes over center to force the moving contact 44 downwardly away from the upper fixed contact 42 to the lower contact 45.

It will be appreciated that it would be possible to utilize the above construction without the guide tongue 40 in the switch but in that case it is necessary to reduce the clearance between the spring seat boss and the housing so as to obtain guidance at that point. This runs the risk of some friction but, on the other hand, simplifies the switch blade.

In the construction shown in FIGS. 3 and 4 the spring seat assembly is eliminated and the seat function is incorporated in the central boss. In this version the diaphragm 50 is provided with a diaphragm plate or pad 52 which is provided with a central integral actuating post 54 which is formed and struck up from the plate itself. As can be seen in the detailed view, opposed slots are formed in the upstanding sides so as to provide the open slot receiving the actuating tongue of the switch blade while the guide tongue 40 fits over the upstanding central portion of the post. The trip spring seats directly on the post right above the guide tongue. It is quite apparent there is no need for a separate spring seat and the upper portion of the housing has been changed considerably to reflect the need of only varying the compression of the trip spring. The operation of this modification is substantially the same as the first, the only difference being that in this version there is no spring seat, this function having been taken over in the central post struck up from the diaphragm plate. The entire assembly is still guided by the guide tongue which is incorporated in the switch blade.

We claim:

1. A pressure switch comprising a housing,

a diaphragm in the housing with one side exposed to pressure variations,

a diaphragm plate carried by the diaphragm in the central portion thereof,

an integral post extending from the plate,

a snap switch mounted in the housing and including an actuating tongue having a lost-motion connection with the post to be actuated in accordance with pressure variations,

spring seat means operatively connected to the post,

spring means seated on the seat means and acting to oppose movement of the diaphragm under influence of rising pressure,

said switch including a separate guide tongue engaging the post to constrain the diaphragm post to generally linear travel over a prescribed path.

2. A pressure switch according to claim I in which the seat means includes a boss projecting loosely through the housing and engaged by the diaphragm plate post.

5. A pressure switch according to claim 4 in which the post includes spaced shoulders between which the actuating tongue of the switch is engaged to provide the lost-motion connection. 

1. A pressure switch comprising a housing, a diaphragm in the housing with one side exposed to pressure variations, a diaphragm plate carried by the diaphragm in the central portion thereof, an integral post extending from the plate, a snap switch mounted in the housing and including an actuating tongue having a lost-motion connection with the post to be actuated in accordance with pressure variations, spring seat means operatively connected to the post, spring means seated on the seat means and acting to oppose movement of the diaphragm under influence of rising pressure, said switch including a separate guide tongue engaging the post to constrain the diaphragm post to generally linear travel over a prescribed path.
 2. A pressure switch according to claim 1 in which the seat means includes a boss projecting loosely through the housing and engaged by the diaphragm plate post.
 3. A pressure switch according to claim 2 in which the post and boss have spaced apart shoulders at the interface of the connection therebetween and the actuating tongue is positioned between the shoulders.
 4. A pressure switch according to claim 1 in which the seat means is an integral part of the post.
 5. A pressure switch according to claim 4 in which the post includes spaced shoulders between which the actuating tongue of the switch is engaged to provide the lost-motion connection. 